The invention relates to a liquid, transparent mixture which is based on lactitol and is very suitable for use as a sweetener and contains appreciably fewer calories than sugar.
Such a mixture is disclosed in WO 95/26644, which describes a syrup containing 1-56% by weight of lactitol, 30-95% by weight of a polydextrose, 0-10% by weight of liquid and 4-69% by weight of water, the polydextrose being a polymer obtained by polycondensation of glucose in the presence of sorbitol and citric acid and it being possible, according to Example 1, for the lactitol:polydextrose ratio to be 60:40. The use of polydextrose, however, has the disadvantage that it contains still residual sugars which may render a brown colour to the mixture and/or to the product prepared from this mixture.
Such liquid mixtures are also disclosed by John A. Van Velthuijsen in J. Agric., Food Chem., Vol. 27, No. 4, pages 680-686, where the preparation of a lactitol syrup by hydrogenating a lactose solution at elevated temperature and pressure in the presence of a Raney nickel catalyst is described. In this way, lactitol monohydrate and a lactitol syrup having a concentration of 64% are obtained after crystallization. If mixed with sorbitol, a lactitol syrup is obtained which has a concentration of 70%.
It has been found, however, that a lactitol syrup prepared in the way described above is unstable and cannot be stored for a fairly long time without crystallization of the dissolved lactitol occurring. Moreover, it has been found that the lactitol syrup prepared in the way described above contains too many impurities in the form of byproducts of the hydrogenation of lactose. In addition, it has been found that the lactitol/sorbitol syrups described are unsuitable for incorporation in, for example, hard-boiled sweets such as acid drops because, owing to the high hygroscopicity of the sorbitol, absorption of water occurs at the outside of the sweets, as a result of which they become sticky and more difficult to handle. Such hard-boiled sweets can therefore not be stored for a long time. Moreover, the sensory profile of sorbitol is not optimum: lactitol and maltitol, for example, have a more pleasant taste.
The object of the present invention is therefore to provide a stable syrup which has a high lactitol content and which can be stored for a fairly long time without crystallization of the lactitol occurring.
A syrup having a relatively high concentration of lactitol is also attractive from an economic point of view because of the greater volume of lactitol which can be transported in liquid form. In addition, a solution having a lower concentration of dissolved solids (lactitol) is also more rapidly liable to microbiological decay. The object of the invention is therefore also to provide a lactitol-containing syrup which is microbiologically stable. Moreover, the object of the invention is to provide a lactitol-containing syrup which has an excellent sensory profile and which is pre-eminently suitable for use as a sweetener in foodstuffs, especially in hard-boiled sweets, the quality and stability of the foodstuffs in terms of sweetness and resistance to moisture absorption being very good over a long time.
The above objects are: achieved by the present invention, which relates to a transparent, liquid mixture containing:
(a) 60-80 per cent by weight (% by weight), preferably 65-75% by weight of dissolved solids comprising, on the one hand, lactitol and, on the other hand, other polyols and/or hydrogenated polydextrose in a lactitol:other polyols and/or hydrogenated polydextrose weight ratio of from 40:60 to 80:20, and
(b) 20-40% by weight, preferably 25-35% by weight, of water,
at least 80% by weight of the other polyols and/or hydrogenated polydextrose being composed of hydrogenated saccharides made up of two or more dextrose units, said proportions being based on the total weight of other polyols.
Lactitol is a known sugar alcohol or polyol obtained by hydrogenation of the glucose part of the disaccharide lactose. For use in the mixture according to the invention both hydrated lactitol and anhydrous lactitol can be used. As regards the lactitol in hydrated form, the nonhygroscopic crystalline lactitol monohydrate is especially suitable. Said lactitol monohydrate is commercially obtainable in very pure form, for example under the brand name LACTY. However, lactitol dihydrate or lactitol anhydrate can be used.
Because the mixture according to the invention is a liquid, it is preferable to start from the lactitol reaction mixture obtained after the hydrogenation of lactose. Said reaction is usually performed in an aqueous medium in the presence of a suitable hydrogenation catalyst. The lactitol solution in water obtained after filtration, purification and possibly concentration by evaporation is very suitable as a source of lactitol for the preparation of the mixture according to the invention. The condition for using such a solution is, however, that the lactitol solution is sufficiently pure, that is to say at least 90% by weight, and preferably 95% by weight, of the content of dissolved solids is composed of lactitol. The advantage of using such a lactitol is that no crystallization step is necessary to obtain crystalline lactitol monohydrate or crystalline lactitol dihydrate which then has to be redissolved. The advantage of using a crystalline lactitol hydrate is the high purity (usually more than 97% by weight of lactitol).
At least 80% by weight, preferably 85% by weight, of the other polyols which may in addition to lactitol form component (a), based on the total weight of other polyols, are composed of hydrogenated saccharides which are made up of two or more dextrose units. In this connection, both a hydrogenated dextrose unit and an unhydrogenated dextrose unit count as a dextrose unit. Such hydrogenated saccharides therefore comprise maltitol (hydrogenated maltose, made up of 2 dextrose units), hydrogenated oligosaccharides composed of 3-6 dextrose units and hydrogenated polysaccharides which contain 7 or more dextrose units. Apart from that, the term xe2x80x9chydrogenatedxe2x80x9d as used in this connection relates especially to the terminal (reducible) dextrose unit of the relevant saccharide. The addition of hydrogen usually takes place at said terminal dextrose unit. Any proportion remaining up to 100% by weight of the other polyols which is not composed of hydrogenated saccharides made up of 2 or more dextrose units is primarily formed by hydrogenated monosaccharides, such as sorbitol and mannitol.
It has been found that it is particularly advantageous if the other polyols contain at least 5% by weight of maltitol, referred to the total weight of other polyols. Maltitol has in fact attractive sweetening properties and has a sweetening power which is greater than that of hydrogenated oligosaccharides and polysaccharides. On the other hand, maltitol is more hygroscopic than oligosaccharides and polysaccharides. Within the quantity of hydrogenated saccharides made up of 2 or more dextrose units, the weight ratio between maltitol, on the one hand, and the hydrogenated saccharides made up of 3 or more dextrose units (Dex3+) on the other hand, can vary within wide limits. The maltitol:Dex3+ weight ratio may appropriately vary from 1:20 to 15:1, preferably from 1:10 to 12:1. Examples of commercially obtainable saccharide mixtures or polyol mixtures which can be used as other polyols in addition to lactitol in component (a) of the mixture according to the invention are polyol mixtures which are sold under the brand names HYSTAR, for example HYSTAR 3375 and HYSTAR 6075, and MALTIDEX, such as MALTIDEX 080, MALTIDEX 085 and MALTIDEX 100.
Instead of or in addition to the hydrogenated oligosaccharides and polysaccharides described above or polyols, the mixture according to the invention may also contain polydextrose in hydrogenated form. Hydrogenated polydextrose is usually obtained by polymerization of dextrose with citric acid and/or sorbitol as possible comonomers, followed by hydrogenation, and is obtainable commercially. The advantage of hydrogenated polydextrose over unhydrogenated polydextrose is that the former no longer contains residual sugars, which may impart a brown colour to the mixture or to a product prepared from the mixture.
As stated, the weight ratio between lactitol, on the one hand, and the other polyols and/or hydrogenated polydextrose, on the other hand, should have a value of 40:60 to 80:20. With a weight ratio between these limits, the mixture according to the invention has a good stability. It has been found, however, that a weight ratio from 60:40 to 80:20, preferably from 68:32 to 76:24, results in an optimum stability of the mixture.
The mixture according to the invention can be manufactured by means of the known methods. Thus, the mixture according to the invention is manufactured by mixing a crystalline lactitol hydrate, for example the monohydrate, with the other polyols and/or hydrogenated polydextrose and water in quantities such that the lactitol:other polyols weight ratio has a value of from 40:60 to 80:20 and that the total quantity of dissolved solids varies from 60 to 80% by weight. A method which can advantageously be used proceeds from a lactitol solution which is obtained from the hydrogenation of lactose in an aqueous medium followed by filtration, purification and possibly concentration by evaporation. The other polyols are then added to said lactitol solution.
The mixture according to the invention is in principle a viscous, colourless, liquid solution or syrup which is very stable as such and can be stored a fairly long time. The mixture according to the invention is especially very suitable as sweetener in a number of foodstuffs, especially in hard-boiled sweets (hard sweets, acid drops, lollies and the like), soft confectionery (inter alia, liquorice and chewing gum), ice-cream products, dessert products and bakery products (biscuits, cake, pastry and the like). For incorporation in such foodstuffs, a sweetener in liquid form is to be preferred to a sweetener in solid form. As sweetener, lactitol has the advantage over sugar that it has a lower calorific value.
During incorporation in foodstuffs, and especially in hard-boiled sweets, the mixture according to the invention will usually be heated together with the other ingredients, as a result of which the water present in the mixture evaporates and the lactitol and the other polyols and/or the hydrogenated polydextrose will remain behind in the ratios specified above. The advantage of the chosen ratios between the various saccharide ingredients is that complete crystallization of the saccharide ingredients does not occur in the final product, which would result in white, dull blemishes and the product would therefore have an unattractive appearance. On the other hand, the chosen ratios result in the formation of only a few crystals or of a thin, transparent crystal layer, which give the final product both an attractive appearance and a good stability in the sense of resistance to moisture absorption. Moreover, the chosen ratio has the advantage that cold flow does not occur; the nondeformability is high and flow of the saccharide ingredients does not occur.
The invention finally also relates to foodstuffs which incorporate the mixture according to the invention.